BIOL 240 Exam 3

What do pseudo-unipolar neurons do?

Carry information from periphery to CNS

What do unipolar neurons do?

Transmit sensory signals; common in PNS sensory neurons

What do bipolar neurons do?

Transmit sensory input (vision, smell, hearing)

What do multipolar neurons do?

Versatile; can be sensory, motor, or interneurons

What is the abundance of most to least abundant neuron type?

multipolar, bipolar, unipolar/ pseud-unipolar

What is the ratio of sensory to motor neurons?

20:1 in favor of sensory

What does the CNS consist of?

Brain and spinal cord

What does the PNS consist of?

Includes spinal and cranial nerves

What is the PNS divided into?

Afferent and efferent neurons

What is the afferent subdivision?

Sensory; go in to

What is the efferent subdivision

Motor; to leave

What are ganglia?

Mass of neuron cell bodies located outside the CNS

What is chromatophilic substance?

Membranous sacs in the cytoplasm of nerve cells that have ribosomes attached to their surfaces

What are collaterals?

Branches from axons

What are Schwann cells?

Neuroglia in the PNS that encase large axons of peripheral neurons in lipid sheaths

What are nodes of ranvier?

Gaps in the myelin sheath along axons of neurons in the PNS

What are oligodendrocytes?

Type of neuroglia the produces myelin in the CNS

Characteristics of a multipolar neuron

Has many processes; one axon and many dendrites

Characteristics of a bipolar neuron

Two processes; one arising from either end

Characteristics of unipolar neurons

Sing process; functions as a single axon

Where are multipolar neurons found?

Ganglia and specialized part of eyes

Where are bipolar neurons found?

Specialized parts of eyes, nose, and ears

Where are unipolar neurons found?

Ganglia

What are sensory neurons?

Conduct impulses from peripheral partes of the body; most are unipolar

What are interneurons?

Lie within brain and spinal cord; most are multipolar

What are motor neurons?

Neurons of the somatic nervous system; are multipolar

What are the four types of neuroglia in the CNS?

Astrocytes, oligondendrocytes, microglia, and ependyma

What are astrocytes?

Star-shaped neuroglia that connects neurons to blood vessels in the CNS and aid in metabolism of glucose

What are oligodendrocytes?

Resemble astrocytes; are smaller with fewer processes; form rows along axons and myelinated axons

Unique characteristic of oligodendrocytes?

May myelinate many axons

What are microglia?

Small cells with fewer processes; help support neurons phagocytize bacterial cells and debris

Characteristics of ependyma?

Cuboidal or columnar cells in chape that may have cilia; form membranes

At what voltage does the resting membrane change?

-70 mV

What happens when the resting membrane changed?

Na+ channels open ad Na+ flows in making the cell less negative

What voltage is threshold potential at?

-55 mV

What happens with threshold potential is reached?

Action potential starts where charge rapidly increases

What is depolarization?

When the inside and outside of neuron are both positive

What causes repolarization?

When potassium channels in the membrane open after depolarization

What is repolarization?

When potassium ions diffuse inward repolarization the membrane; where polarity between inside and outside are reestablished

What is hyperpolarization?

Where potential temporarily dips below -70 mV. The Na+/K+ pumps move Na+ out and K+ in

What is saltatory conduction?

Impulse conduction along a myelinated axon that seems to jump from one node to the next

Acetylcholine

Stimulates skeletal muscle contraction; may excite or inhibit at autonomic nervous system

Examples of monoamines

Epinephrine, norepinephrine, dopamine, and seratonin

Norepinephrine

May excite or inhibit autonomic nervous system actions, depend on receptors

Dopamine

Limited actions in the autonomic nervous system; may excite or inhibit

What are neuronal pools?

Groups of neurons that synapse with each other to perform a common function in the CNS

What are meniges?

Three connective tissue membranes; dura mater, arachnoid mater, and pia mater

What is the cerebrum?

Part of the brain in the upper part of the cranial cavity that provides higher mental functions

What does the cerebral cortex do?

Provides higher brain functions divided into sensory, association, and motor areas

What is the role of the postcentral gyri?

Provides the sensations of temperature, touch, pressure, and pain in the skin

Where are the association areas of the brain?

In the anterior portion of the frontal lobes, and lateral portions of the parietal, temporal, and occipital lobes.

What do association areas of the brain do?

Analyze and interpret sensory experiences and help provide memory, reasoning, verbalizing, judgement, and emotions

Motor areas of the cortex?

Lie in the precentral gyri of the frontal lobes; contain pyramidal cells

What are basal nuclei?

Masses of gray matter deep within the cerebral hemispheres

What is the diencephalon?

Part of the brain from the posterior forebrain and located between cerebral hemisphere and superior to the brainstem

How many pairs of spinal nerves are there?

31 Pairs

How many pairs of cranial nerves are there?

12

Cranial nerve 1

Olfactory; sensory; smell

Cranial nerve 2

Optic; sensory; sense of vision

Cranial nerve 3

Oculomotor; primary motor; motor fivers to muscles that raise and focus eyes

Cranial nerve 4

Trochlear; primary motor; Impulses that move the eyes

Cranial nerve 5

Trigeminal; mixed; Ophthalmic, maxillary, and mandibular divisions

Cranial nerve 6

Abducens; primary motor; Moe the eyes

Cranial nerve 7

Facial; mixed; taste and sensory in the nose and palate

Cranial nerve 8

Vestibulocochlear; sensory; sense of equilibrium

Cranial nerve 9

Glossopharyngeal; mixed; impulses of throat and swallowing

Cranial nerve 10

Vagus; mixed; neck, chest, and abdomen

Cranial nerve 11

Accessory; primary motor; Soft palate and in the neck

Cranial nerve 12

Hypoglossal; primary motor; impulses to move the tongue

What is the cervical plexus?

C1-C4; supply muscles of skin and neck and diaphragm

What is the brachial plexus?

C5-T1; deep in shoulder and axillae

What is the lumbosacral plexus?

L1-S4;

Proprioceptors are what class of receptor?

Mechanoreceptor

What type of photoreceptor is mor4e sensitive to light and can, therefore, provide vision in dim light?

Rods

What types of structures are temperature receptors?

Free nerve endings

Muscle spindle and Golgi tendon organs are receptors for ___

Proprioception

What is the destination of fibers of the spinothalamic tracts transmitting pain and temperature information?

Thalamus

What structure produces tears?

Lacrimal gland

What stimulates Golgi tendon organs?

A muscle is stretched nearly to its limit

What are the saccule and utricle responsible for?

Static equilibrium

What is the semicircular canal responsible for?

Dynamic equilibrium

What is the cochlea responsible for?

Hearing

Where are the saccule and utricle located?

Inner ear region

Where is equilibrium sensed?

Maculae and cristae ampullaris

What causes the lens of the eye to thicken?

Ciliary muscles contracts

What is the function of a stretch reflex?

To contract a muscle that is stretched

List the components of the middle (vascular) layer of the wall of the eye

Ciliary body, iris, and choroid coat

How do pain receptor differ from other somatic receptors?

They adapt very little, if at all

The auditory tube runs between the throat and the ____

Middle ear

What is detected by the hair cells in the semicircular canals?

Direction of motion

What structure separates the two cerebral hemispheres?

Falx cerebri

Where is the pia mater located?

Deep to the arachnoid mater

Which type of secretion enters the interstitial fluid and affects neighboring cells in the same tissue?

Paracrine secretion

What is found within the dural sinuses?

Venous blood

____ Secretions are released from one cell and alter the functioning of neighboring cells

Paracrine

____ Secretions have their effect on the same cell that released them

Autocrine

The cerebral cortex is made up of ____ matter, consisting of _____

Gray; neuron cell bodies and synapses

What is contained within the epidural space in the vertebral column?

Loose connective tissue, blood vessels, and adipose tissue

Where are axons of somatic motor neurons located?

Anterior root